It is possibly the greatest of American political myths, repeated ad nauseam by presidential candidates in their election campaigns. President Barack Obama has claimed that the United States enjoys a special bond with Israel unlike its relations with any other country. He has called the friendship "unshakeable", "enduring" and "unique", "anchored by our common interests and deeply held values". His Republican rival, Mitt Romney, has gone further.Politicians may prefer to express undying love for Israel, and hand over billions of dollars annually in aid, but the US security establishment has -- at least, in private -- always regarded Israel as an unfaithful partner.

The distrust has been particularly hard to hide in relation to Iran…. While coverage has focused on the personal animosity between Obama and the Israeli prime minister, Benjamin Netanyahu, the truth is that US officials generally are deeply at odds with Israel on this issue. The conflict burst into the open this month with reports that the Pentagon had scaled back next month's joint military exercise, Austere Challenge, with the Israeli military that had been billed as the largest and most significant in the two countries' history….

Israel is far from a trusted ally in the US "war on terror". A former intelligence official told the Associated Press in July that Israel ranked lower than Libya in a list of countries helping to fight terrorism compiled by the Bush administration after September 11.

So why all the talk of a special bond if the relationship is characterized by such deep mistrust?

Part of the answer lies in the formidably intimidating tactics of the pro-Israel lobby in Washington. Thomas Friedman, the New York Times columnist, spoke for a growing number of observers last year when he wrote that the US Congress was effectively "bought and paid for" by Israel's lobbyists….

But there is another, less spoken-of reason.... [Israel] realized that -- once it possessed the only nuclear arsenal in the Middle East -- the US would rarely risk standing in its way, however much its policies ran counter to US interests.

For that reason, if no other, Israel is determined to stop any rival, including Iran, from getting a nuclear weapon that would end its monopoly.